Max Bore on a 98 Magnum 360?

I'm a 318 guy, but if I had this block freshly done up, I'd definitly get it sonic checked and use it if it proved to be OK. As stated above, your machinist may have done this already, and if not they should do it gratus since they overbored your request without talking to you first. With the HP numbers you are trying to achieve, you'd be way better off with the 360. JMO, Mike